question_answer

An ammeter and a voltmeter of resistance R are connected in series to an electric cell of negligible internal resistance. Their readings are A and V respectively. If another resistances is connected in parallel with the voltmeter, then

A) both A and V will increase

B) both A and V will decrease

C) A will decrease and V will increase

D) A will increase and V will decrease

Correct Answer: D

Solution :

When resistance R is connected in parallel with the voltmeter. The effective resistance will decrease. According to Ohm's law                    \[V=IR\]or          \[R=\frac{V}{I}\] Here, R decreases so V should decrease and I should increase.